It is the purpose of this investigation to study the structure- function relationship of the proteins and crystallites involved in the initiation and progress of the calcification process in enamel and dentine. First, the proteins of the developing bovine embryo enamel matrix will be isolated by the special techniques already developed in these laboratories, taking advantage of the unique temperature sensitivity of the matrix proteins as a function of pH and ionic strengths. Macromolecular interactions and conformations will be investigated by all the appropriate techniques, including circular dichroism, ultracentrifugation, electrophoresis, electronmicroscopy, etc. Amino acid and other relevant analyses will be made to relate these to the structure and function of these proteins, especially in the light of the strongly hydrophobic nature of the residues and the high relative concentration of proline and histidine. Further, enamel rods in various states of maturation and apatite crystals in high state of purity will be isolated by techniques newly developed in these laboratories and their structural components (proteins, etc.) and surface properties investigated, so as to understand the nature of the relationships that exist between their interfaces.